Wireguard vpn is suddenly interrupted

Accessing the router from the outside using wireguard vpn. In addition, all traffic leading to this router using vpn policy routing is routed to the node vpn.

These configurations work successfully, but after about half a day, they lose connectivity from the outside and must be rebooted and restarted for the router to work.

I want to know how to solve this problem.

The openwrt setting is the same as the Wireguard client + Wireguard server scenario 2 in the link above.

The router is tplink archer c7 v5.
Thank you.

Can you make a comparison of the iptables rules in place before and after the problem occurs?
Especially the mangle chain.